U.S. patent application number 13/578749 was filed with the patent office on 2013-08-08 for photodegradable paper and its use.
This patent application is currently assigned to RHODIA ACETOW GMBH. The applicant listed for this patent is Dirk Holter, Wolfgang Koppe. Invention is credited to Dirk Holter, Wolfgang Koppe.
Application Number | 20130199742 13/578749 |
Document ID | / |
Family ID | 42111004 |
Filed Date | 2013-08-08 |
United States Patent
Application |
20130199742 |
Kind Code |
A1 |
Holter; Dirk ; et
al. |
August 8, 2013 |
PHOTODEGRADABLE PAPER AND ITS USE
Abstract
A photodegradable paper including cellulose fibers and, if
applicable, fillers, additives and/or other kind of fibers is
described. Also described, is a paper particularly in the field of
packaging, tissue papers or cigarettes.
Inventors: |
Holter; Dirk; (Emmendingen,
DE) ; Koppe; Wolfgang; (Merzhausen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Holter; Dirk
Koppe; Wolfgang |
Emmendingen
Merzhausen |
|
DE
DE |
|
|
Assignee: |
RHODIA ACETOW GMBH
Freiburg
DE
|
Family ID: |
42111004 |
Appl. No.: |
13/578749 |
Filed: |
February 10, 2011 |
PCT Filed: |
February 10, 2011 |
PCT NO: |
PCT/EP11/51937 |
371 Date: |
October 25, 2012 |
Current U.S.
Class: |
162/139 ;
162/141; 162/181.5 |
Current CPC
Class: |
D21H 19/38 20130101;
D21H 17/69 20130101; D21H 17/63 20130101; D21H 21/52 20130101; D21H
27/10 20130101 |
Class at
Publication: |
162/139 ;
162/181.5; 162/141 |
International
Class: |
D21H 17/63 20060101
D21H017/63 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 12, 2010 |
EP |
10153510.2 |
Claims
1. A photodegradable paper comprising cellulosic fibers and,
optionally, additives, wherein the photodegradable paper comprises
a carbon modified titanium dioxide.
2. The photodegradable paper as defined in claim 1, wherein the
cellulosic fibers originate from a source selected from the group
consisting of wood, lignocellulose, mechanical pulp, waste paper,
fiber crop or a mixture of two or more of them.
3. The photodegradable paper as defined by claim 1, wherein the
carbon modified titanium dioxide is carbon modified at its
surface.
4. The photodegradable paper as defined by claim 1, wherein the
carbon modified titanium dioxide has a crystallite size of 5 nm to
150 nm.
5. The photodegradable paper as defined by claim 1, wherein the
carbon modified titanium dioxide has a density (ISO 787, part 10)
of 3.0 g/cm.sup.3 to 5.0 g/cm.sup.3.
6. The photodegradable paper as defined by claim 1, wherein the
carbon modified titanium dioxide has a specific surface (BET)
greater than 100 m.sup.2/g.
7. The photodegradable paper as defined by claim 1, wherein the
carbon modified titanium dioxide has, in contrast to not-modified
titanium dioxide, a significant light absorption in the range of
.lamda.>=400 nm.
8. The photodegradable paper as defined by claim 1, wherein the
carbon content of the carbon modified titanium dioxide is in the
range of 0.05 wt % to 5 wt %.
9. The photodegradable paper as defined by claim 1, wherein the
photodegradable paper comprises 0.5 wt % to 40 wt %.
10. The photodegradable paper as defined by claim 1, wherein the
photodegradable paper is at least one part of a packaging
material.
11. The photodegradable paper as defined by claim 1, wherein it is
a paper tissue.
12. The photodegradable paper as defined by claim 1, wherein it is
a part of a cigarette.
13. The photodegradable paper as defined by claim 12, wherein the
paper is a cigarette paper, a plug wrap and/or a tipping.
14. The photodegradable paper as defined by claim 12, wherein the
filter material of the cigarette also comprises a carbon modified
titanium dioxide.
15. The photodegradable paper as defined by claim 4, wherein the
carbon modified titanium dioxide has crystallite size of from 7 nm
to 25 nm.
16. The photodegradable paper as defined by claim 5, wherein the
carbon modified titanium dioxide has a density of 3.5 g/cm.sup.3 to
4.2 g/cm.sup.3.
17. The photodegradable paper as defined by claim 6, wherein the
carbon modified titanium dioxide has a specific surface (BET)
greater than 250 m.sup.2/g.
18. The photodegradable paper as defined by claim 8, wherein the
carbon content of the carbon modified titanium dioxide is in the
range of 0.3 wt % to 1.5 wt %.
19. The photodegradable paper as defined by claim 9, wherein the
photodegradable paper comprises 2 wt % to 25 wt % of carbon
modified titanium dioxide.
20. The photodegradable paper as defined by claim 10, wherein the
packaging material is a food packaging material.
Description
[0001] The invention relates to a photodegradable paper containing
cellulosic fibers and, if applicable, fillers, additives and/or
other kind of fibers. This invention further relates to the use of
such a paper particularly in the field of packaging, tissue papers
or cigarettes.
[0002] Normally, paper products are recycled after use or brought
to a waste disposal system. But there are also papers, which get
into the environment, predominantly the food packaging, cigarette
papers or tissue papers.
[0003] Paper products, which go or can go into the environment at
the end of their life cycle, should be rapidly degraded, in order
to limit the damage on the environment. In some applications, e.g.
cigarette filter wrappings, the degradation of the paper is the
prerequisite to start the degradation of enclosed materials.
[0004] Generally, papers consisting mainly of cellulose fibers are
recognized as biodegradable. But depending on the environmental
conditions or on the paper finish, the degradation can take a long
time and in this case the paper contributes significantly to
environmental pollution. This is especially the case, if the paper
lies on a surface with insufficient conditions for the development
of microorganisms, necessary for the biodegradation of the
cellulose material, and if there is a lack of water or if the paper
contains a finish preventing it to disintegrate in contact with
water. Under these conditions an additional mechanism is necessary
for a sufficient degradation of the material. In particular photo
catalytic degradation by the exposure to light can be relevant in
these cases. The photo catalytic degradation can be the exclusive
mechanism leading to the complete degradation of the material, but
it can also support other degradation mechanisms, such as
biodegradation.
[0005] It is well known, that titanium dioxide, especially in form
of anatase, can break down organic materials by photo catalytic
reaction. Anatase absorbs light in the UV range of the light
spectra. This energy excites electrons resulting in the
transformation of water and oxygen into radicals which attack
organic materials. This degradation of materials generally impairs
their normal function. Therefore, much work was done on the
stabilization of titanium dioxide containing materials. Examples of
stabilization in plastic materials can be found in U.S. Pat. No.
2,206,278, GB 780,749 and U.S. Pat. No. 3,961,975.
[0006] Although photo degradation is not considered as a serious
problem for common paper applications compared to other
deterioration and degradation mechanisms of paper, there are works
dealing with photo degradation or photo degradation accelerated by
pigments, e.g. zinc oxide or titanium dioxide (U.S. Congress,
Office of Technology Assessment, Book Preservation Technologies,
OTA-0-375, Washington, D.C.: U.S. Government Printing Office, May
1988; L. Campanella et al, Ann. Chim., 95, 2005, 727-740). Titanium
dioxide is used in paper industry for special papers as filler and
as coating pigment with high brightness and opacity (Ullmann's
Encyclopedia of Industrial Chemistry, 6.sup.th ed., 2003).
[0007] During the last years titanium dioxide has got more into the
focus of the development of air purification systems with paper as
pigment carrier (e.g. in form of wall papers). In those cases the
objective is to destroy hazardous or odorous substances in the air
by photo degradation catalyzed by titanium dioxide, but to maintain
the paper carrier in its entirety (T. Tanaziki et al., Journal of
Health science, 53, 2007, 514-519; JP 08173805; JP 08173763). U.S.
Pat. No. 5,817,427 is concerned with a titanium dioxide containing
paper used as a deodorizing element. Activated by light, many
hazardous organic substances including malodorous substances are
decomposed by oxidation. But it was also observed that the applied
ultra fine titanium dioxide, besides the targeted substances, can
also oxidize and decompose the paper matrix, which therefore must
be protected.
[0008] In special applications, not-stabilized titanium dioxides
were deliberately incorporated into plastics to increase the
degradation of the material. The titanium dioxide was used in its
anatase form, sometimes in combination with photo-degradation
accelerating additives.
[0009] DE 24 36 260 C1 describes the use of titanium dioxide
pigments with small particle diameters for targeted degradation of
plastic compounds by the influence of weather and/or light. In CA
1073581 the application of titanium dioxide particles for photo
catalytic degradation of polyolefins was disclosed.
[0010] WO-A-93/24/24685, EP 716 117 A1, U.S. Pat. No. 5,491,024 as
well as U.S. Pat. No. 5,647,383 are dealing with accelerated photo
catalytic degradation of cellulose esters.
[0011] The object of the present invention is to provide a paper,
which shows a significantly enhanced photo degradation under
environmental conditions. Furthermore the invention is directed to
the use of this photodegradable paper particularly when the paper
is not recycled: this concerns especially certain packaging, tissue
papers (as for instance paper towel, handkerchief etc.), or papers
used in the production of cigarettes (cigarette paper, plug wrap,
tipping).
[0012] At this end, the invention proposes a paper, in which a
carbon modified titanium dioxide, which is photo catalytically
active, is incorporated.
[0013] The introduction of a carbon modified titanium dioxide in
the paper resulted in an unexpected high acceleration of the photo
degradation of the paper both in UV-range and in visible range of
the light spectra.
[0014] The term "carbon modified" means "modified by elemental
carbon". The scientific literature describes this carbon
modification, for instance in the following publications: S.
Sakthivel, H. Kisch, Angew. Chem., Int. Ed. 2003, 42, 4908-4911; K.
S. Raja et al, J. Power Sources 2006, 161, 1450-1457; C. Xu et al.,
Appl. Catal., B 2006, 64, 312-317; Y. Li et al., Chem. Phys. Lett.
2005, 404, 25-29; M. Janus et al., Appl. Catal., B 2006, 63,
272-276). Normally, this modification is done by carbonization of
an organic substance in contact with the material or with
precursors of the material, which is to be modified but also by
oxidation of metal carbides. Depending on the production process
and the material which is modified with carbon, the carbon can be
found in the final product in form of larger structures (e.g.
layers, clusters) or in form of single carbon atoms. The carbon can
be located within the material and/or on its surface.
[0015] The titanium dioxide according to the present invention is
carbon modified in the whole volume or at its surface. Preferably,
a carbon modified titanium dioxide is used, whose surface is carbon
modified. By the modification the band gap of the semiconductor
titanium dioxide is reduced, and in comparison to not-modified
titanium dioxide light of longer wavelength can also be used for
the excitement of a valence band electron so that the photo
catalytic properties are activated.
[0016] The crystal structure of the titanium dioxide of the
invention can be of the rutile type or of the anatase type.
Preferably it is of the anatase type.
[0017] Advantageously the crystallite size of the carbon modified
titanium dioxide is optimized, preferably between 5 and 150 nm,
especially between 7 and 25 nm. In a particular case, it can be
advantageous and even necessary to mill a commercially available
carbon modified titanium dioxide to reduce the size of the
agglomerates. Advantageously the carbon modified titanium dioxide
has a density (ISO 787, part 10) of 3.0 to 5.0 g/cm.sup.3,
especially 3.5 to 4.2 g/cm.sup.3. The specific surface of the
carbon modified titanium dioxide is preferably larger than 100
m.sup.2/g, especially larger than 250 m.sup.2/g. It is especially
advantageous that the carbon modified titanium dioxide presents, in
contrast to not-modified titanium dioxide, a significant light
absorption in the range of .lamda.>=400 nm.
[0018] There are no special limitations for the carbon content of
the carbon modified titanium dioxide. Preferably the amount of
carbon is in the range of 0.05 to 5 wt %, especially from 0.3 to
1.5 wt %.
[0019] Besides functionality, there are no special limitations for
the content of carbon modified titanium dioxide within the paper.
Preferably the content of carbon modified titanium dioxide in the
paper is in the range of 0.5 to 40 wt %, especially 2 to 25 wt
%.
[0020] If needed, besides the carbon modified titanium oxide, other
photo degradation accelerators may be added in the paper. As a
photo degradation accelerator, for example benzoin; benzoin alkyl
ether; benzophenone and its derivatives, such as
4,4'-bis(dimethylamino)benzophenone; acetophenone, such as
alpha-diethoxyacetophenone and derivatives, can be cited.
[0021] The nature of the paper material according to the present
invention, depends on the intended application. The paper can be
based on usual fibers, whose origin is for instance pulp from wood
or other lignocelluloses, mechanical pulp, waste paper, fiber crops
(e.g. cotton, flax, hemp, sisal) or mixtures of two or more of
them. The paper can also contain fibers of other materials, e.g.
man made fibers like PA, PET, PP, PE, PVA, PTFE, PU, PVC, aramides,
PPS or viscose. One or more of usual additives can be added besides
the carbon modified titanium dioxide, e.g. fillers (e.g. kaolin,
calcium carbonate, talc, gypsum), strength additives and binders
(e.g. poly(ethylene imines), PA, urea- or formaldehyde condensates,
starches and their derivatives, plant gums, alginate, cellulose
derivatives, casein, gelatin, PVA, PVP, acrylic resin), sizing
agents (e.g. rosin size, dimeric alkylketenes, aluminium sulfate),
dyes, pigments (e.g. not carbon-modified titanium dioxide, iron
oxide), optical brighteners, chemicals for specialty papers (e.g.
flame retardants, corrosion inhibitors, antioxydants). Some process
aids can be used for the production of paper, like retention aids
(e.g. poly(ethylene imine), polyacrylamide, cationic starches,
carboxymethylcelluloses), defoamers (e.g. mixtures of higher
alcohols, salts of fatty acids, water-emulsible phosphate esters),
biocides, dispersing agents, complexing agents (e.g. EDTA, DTPA,
HEEDTA, oxalic acid salts, citric acid salts), precipitation and
fixing agents, drainage aids, additives for waste paper processing
and deinking. The additives are used in amounts advantageous for
the respective application. These additives are well known for a
man skilled in the art.
[0022] The paper can also contain a biodegradation promoter, such
as cellulose chain splitting enzymes, phosphorus, nitrous and/or
sulfurous additives.
[0023] There is no limitation concerning the introduction method of
the modified titanium dioxide in the paper.
[0024] According to one embodiment of the invention, the modified
titanium dioxide can be introduced in the fibers of the paper.
[0025] According to another embodiment of the invention, which is
preferred, the titanium dioxide is directly introduced in the paper
during its preparation.
[0026] In this case, in contrast to photodegradable polymers, the
titanium dioxide added to paper is not incorporated within a fiber
but distributed between the fibers and the weakening of the fiber
structure obviously occurs by photo catalytic reaction at the
contact points.
[0027] The production of paper according to the present invention
is not limited to any process. Any suitable production process
known in the art can be applied.
[0028] The paper can also be coated, printed or perforated. The
coat or the printing ink can also contain the carbon modified
titanium dioxide of the invention.
[0029] According to a specific embodiment of the invention, when
the paper of the invention is used as a paper of cigarette, the
filter material of the cigarette preferably also contains the
carbon modified titanium dioxide of the invention.
[0030] Other details or advantages of the invention will appear
more clearly in light of the examples given below.
EXAMPLES
[0031] A slurry of the titanium dioxide was prepared by dispersion
in water via ultrasonic sound and setting of the pH to 8 by
addition of NaOH.
[0032] 16.8 g refined birch wood sulfate pulp was watered for 15 h
in 250 ml tap water. This mixture was transferred into a
disintegrator, filled up to 2 l with tap water and disintegrated
for 2 min at 1500 rpm. This suspension was transferred into a
beaker, filled up to 10 l and homogenized for 15 min.
[0033] The titanium dioxide slurry was added to 1 l of the
resulting wood pulp suspension during stirring with 600 rpm and,
subsequently, the mixture was neutralized with 0.5 M sulfuric
acid.
[0034] The paper sheets were prepared on a Rapid-Kothen sheet
former and afterwards dried for 3 min at 93.degree. C. in vacuo
(water jet pump) on the sheet former and subsequently for 2 h at
105.degree. C. in a drying cabinet.
[0035] The resulting example paper sheets contained 15 wt % of the
titanium dioxide
[0036] The slurries were prepared using different titanium
dioxides:
TABLE-US-00001 TABLE 1 Oil absorption BET Carbon Titanium value
Crystallite surface content Example dioxide type (ISO 787/5) size
[m.sup.2/g] [wt %] A anatas pigment 20 ~0.3 .mu.m 9 -- (uncoated) B
ultrafine anatas ~50 ~15 nm >250 -- photocatalyst (uncoated) C
ultrafine carbon ~50 ~15 nm >250 0.8 doped anatas (surface
doped)
[0037] From the example paper sheets stripes of 150 mm length and
15 mm width were cut, and in each case an area of 20 mm length of
these stripes irradiated at a wavelength of 365 nm (Vilber Lourmat
UV irradiation system) with 40 Watt. The irradiation was performed
for 6 and 12 h, respectively.
[0038] The irradiated stripes were stored according to DIN EN ISO
20187 at 23.degree. C. and 50% relative humidity until constant
weight. The paper thickness was measured according to DIN EN ISO
534, the specific mass according to DIN EN ISO 536.
[0039] The E-modulus was measured using a tensile tester.
[0040] The determined reductions of the E-moduli are summarized in
Table 2.
TABLE-US-00002 TABLE 2 Reduction [%] of E-modulus versus time of
irradiation 0 hours 6 hours 12 hours Example A 0 2 3 Example B 0 3
3 Example C 0 11 18
* * * * *